Gaps is an ear training tool that listens to what you play on guitar. It will help you train your ear and your fretboard visualization skills simultaneously.
Gaps focuses on teaching you to recognize and locate scale degrees. Scale degrees are the individual notes that relate to a key. Being able to hear these degrees will help you out in learning music by ear, transcription and composition.
Because you need to use your guitar as a input, you'll also gain a ton of practice in locating these degrees in the many positions in which they can appear on the guitar neck. This will help you out tremendously in being able to improvise music and effectively use scales anywhere on the neck.
You can find more info at: https://gapsguitar.com/